Ftyjtk

I have an issue with handling parallel requests with cloud functions.
My scenario is to select a driver from the db and update its status.

I do check for that status property before updating it, but when I send multiple requests (database on create triggers to be specific) within a second it doesn't seem to read the updated status property.
And it always updates with the information of the last request.
I also have noticed that sometimes the requests are processed altogether.

What can I do to fix these issues?

index.js

const db = app.database();

const TripManagementUtil = require('./utils').TripManagementUtil;



exports.triggerNotifications = functions.database.ref('/Trip/{pushId}').onCreate( (snapshot, context)  => 

{

    var newTrip = snapshot.val();

    var tripKey = context.params.pushId;

    var tripManagementUtil = new TripManagementUtil();

    tripManagementUtil.searchDrivers(tripKey, newTrip, db);    

});

utils.js

searchDrivers(tripKey, trip, db){



    const results = ;

    var lat = trip.pickupLocation.lat, long = trip.pickupLocation.lng;

    var vehicleTypeID = trip.vehicleTypeID;

    var alreadyAssigned = trip.alreadyAssigned;

    var self = this;



    if(alreadyAssigned == null || alreadyAssigned == 'undefined'){

        alreadyAssigned = ;

    }



    const geofireQuery = new GeoFire(db.ref('vehicleLocation').child(vehicleTypeID + "")).query({

        center: [lat, long],

        radius: constants.searchRadius

    })

    .on('key_entered', (key, coords, distance) => {

        if(alreadyAssigned.indexOf(key) == -1){

            var result = {

                driverID: key,

                distance: distance

            }

            results.push(result);

        }  

    });

    setTimeout(() => {



        geofireQuery.cancel(); 



        if (results.length === 0) {

            self.noDriversHandler(alreadyAssigned, tripKey, db);

        } else {

            results.sort((a, b) => a.distance - b.distance);

            var driversAvailable = false;

            var index = 0;

            function checkDriver(){

                db.ref().child("driver").child("available").child(results[index].driverID).once('value').then(function(vehicleSnap){

                    var vehicle = vehicleSnap.val();

                    if(!driversAvailable){

                        if(vehicle != null && vehicle.vehicleTypeID == vehicleTypeID

                            && (vehicle.tripStatus != TripVehicleActionEnum.DriverConfirmed && vehicle.tripStatus != TripVehicleActionEnum.VehicleAssigned)

                            && alreadyAssigned.indexOf(vehicle.driverID +"") === -1){

                            driversAvailable = true;

                            self.driverExistsHandler(trip, tripKey, alreadyAssigned, vehicle, db);  

                        }

                        if(!driversAvailable && index + 1 == results.length){

                            self.noDriversHandler(alreadyAssigned, tripKey, db);

                        }  

                        index++;  

                    }

                    else{

                        index++;

                        checkDriver();

                    }

                });

            }

            checkDriver();

        }    

    }, 1500);

}

To write data to the database where the value is based on an existing value, you'll want to use Firebase Realtime Database transactions. For more on this, and examples, see save data transactionally in the Firebase documentation.